Acid chloride-fluoride bath for nickel plating



Patented Feb. 24, 1948 ACID CHLORIDE-FLUORIDE BATH FOR NICKEL PLATINGArthur H. Du Rose, Euclid, Ohio, assignor to The Harshaw ChemicalCompany, Elyria, Ohio, a r

, corporation of Ohio No Drawing. Application MarchlZ, 1945,

Serial No. 582,423

3 Claims. (Cl. 204-49,)

This invention relates toeleotrodeposition of nickel from high chloridesolutions, and more particularly a chloride-fluoride bath omittin boricacid.

I have now discovered that the use of certain fluorides in nickelplating solutions of the high chloride type instead of the usual boricacid buifer is advantageous in respect to ductility of the resultingdeposit, throwing power and freedom from pitting. The solution alsoremains clear at pH values above 5.0 whereas the usual bath bufferedwith boric acid becomes turbid. There is also a slight increase inbrightness in the all chloride solution and solutions in which thenickel in solution is more than half derived from chloride.

By high chloride solutions I mean those in which at least 33 of thenickel is from chloride, the remainder from sulfate.

As is well known, all-chloride nickel plating solutions normally yieldmore highly stressed deposits than do solutions high in sulfate, Withthe advent of equipment suitable for containing the all-chloridesolution there has been substantial tendency in the last few years forWorkers in the art of nickel plating to experiment with solutions of theall-chloride or high-chloride type in an attempt to produce deposits nomore highly stressed than those taken from the usual highsulfatesolutions. Surprisingly, the use of fluorides as described below resultsin marked reduction in stress in the deposit. For example, a halfchloride bath using fluorides gives a, deposit which is no more highlystressed than those derived from the normal high-sulfate bath. Thiscomparison is between solutions buffered with fluoride on the one handand with boric acid on the other, 15 to 30 grams per liter of NH4HF2 orequivalent fluorine content of other fluorides as described belowcompared with 37.5 grams per liter of boric acid in standard Watts bath,these being optimum concentrations in both cases. Still moresurprisingly, the use of fluorides as described below gives improvedresults in respect to throwing power, pitting, brightness and bufieringaction.

Fluorides suitable for my purpose are HF, NaF, KHFz, NHiHFz, NiFz, andNiHF. These are used in quantity between 15 and 30 grams per liter inthe case of NHiHFz and in the other cases the equivalent in fluorinecontent of 15 to 30 grams per liter of NH4IIF2.

Suitable bath compositions are as follows:

Nickel chloride hexahydrate 33%? to 1007 .grems per liter.. 200 toNickel sulfate hexahydrate ee%%m 0%.? v410...} 40o A substance of theclass consisting of NHiHFQ, HF, NaF,

KHFi, NiFi, and NiHF and mixtures of a plurality thereof, the totalfluorine content thereof being equivalent to iHFi grams per Men. 15 to30 Water Remainder pH (may be adjusted with H01) 2.5 to 5.5

Specific examples of preferred bath proportions according to theinvention are as follows:

Having thus described my invention, what I' claim is:

1. A nickel plating solution essentially consisting of water from 200 to400 grams per liter of a source of nickel of the class consisting of (l)nickel chloride and (2) nickel chloride plus nickel sulfate, inproportion such that at least 33 of the nickel is from the chloride, HClsuiflcient to produce a pH of from 2.5 to 5, and a source of fluorine ofthe class consisting of NH4HF2, HF, NaF, KHFz, NiF'z, NiHE and mixturesof a plurality thereof, the total fluorine content of said source offluorine being equivalent to from 15 to 30 grams per liter of NH4HF2.

2. A nickel plating solution essentially consist ing of water, nickelchloride, HCl suflicient to produce a pH of from 2.5 to 5, and from 15to 30 3 grams per liter of a substance of the class consisting ofNH4HF2, HF, NaF, KHFz, NiFz, NiHF and mixtures of a plurality thereof.

3. A nickel plating solution essentially consisting of water, from 200to 400 grams per liter of 5 a source of nickel of the class consistingof (1) nickel chloride and (2) nickel chloride plus nickel sulfate inproportion that at least 50% of the nickel is from the chloride, HCl inquantity sulficient to produce a pH of 2.5 to 5, and a source offluorine of the class consisting of; NHiHFz, HF, NaF, KHFz; NiF2,.NiHF.and mixtures of a plurality thereof, the total fluorine content of saidsource of fluorine being equivalent to from 15 to 30 grams per liter ofNH4HF2.

ARTHUR H, DU ROSE;

REFERENCES CITED The following references-are of record in th file ofthis patent:

UNITED STATES PATENTS Number Name Date Loose Mar. 16; 1943 FOREIGNPA'IEN'IS Number Country Date 513,963 Great Britain Oct. 26, 1939 OTHERREFERENCES Transactions of the Electrochemical Society, vol. '75 (1939)pages 209-211, by W. A. Wesley et al 20 Standards. Nol10l1(1924),page50.

